Pliers having jaw limiting means thereon



Aug. 28, 1956 E. F. AYER 2,

PLIERS HAVING JAW LIMITING MEANS THEREON Filed March 16, 1955 fare-m2 firm/v 784m? r- Amp/Ye) United States Patent PLIERS HAVING JAW LIMITING MEANS THEREON Ermon F. Ayer, North Haven, Conn., assignor to General Hardware Mfg. Co., Inc., New York, N. Y., a corporation of New York Application March 16, 1955, Serial No. 494,635

2 Claims. (Cl. 81-51) This invention relates to pliers and other hand tools manipulated in plier-like fashion and more particularly to the type having means for adjustably limiting the movement of the jaws towards each other as is desirable in wire-stripping pliers, Orthodontists crimping pliers, artisans ships and the like.

An object of this invention is to provide a novel and improved plier-like tool having a stop button which is manually slidable to diiferent positions along a slot track on one of the arms, to effect adjustment of the extent of movement of the jaws towards each other; said button being in the path of the other arm of such tool. The construction is such that the button will remain fast in any set position along the track though acted on by the force applied to close such tool. The necessity of securing the stop button by means of a screw or other suitable fastener to hold it in place, is avoided and provision is made against accidental shifting of the button during handling.

A further object thereof is to provide a novel and improved tool of the character described, afiording rapid and accurate setting of the said button without tools and with only the use of one hand which is that holding the tool.

A further object of this invention is to provide a plier-type tool of the kind set forth which is reasonably cheap to manufacture, easy to use and efiicient in carrying out the purposes for which it is designed.

Essentially, I have provided a frictional means to avoid accidental slippage of the mentioned stop button, and the track therefor is made in such manner that when force is applied to close the plier, the force component acting to move the button at any position, is less than is necessary to move it along such track.

In the accompanying drawings forming part of this specification, similar characters of reference indicate corresponding parts in all the views.

Fig. 1 is a front view of a plier embodying the teachings of this invention. The tool here shown is for stripping the insulation from 03 an end portion of an electric wire the stop button being used to limit the cut so that only the insulation is slit while the wire remains intact.

Fig. 2 is a side view of Fig. 1.

Fig. 3 is an enlarged section taken at lines 3-3 in Fig. 1.

Fig. 4 is a diagrammatic representation of the forces acting on the button when the plier is closed for any setting of said button along its track.

Fig. 5 is a magnified diagrammatic layout of the track slot center line, for the practice of this invention.

In the drawings, the numeral designates generally a wire-stripping plier made up of a pair of arms 16, 17 which are positioned one on the other and joined in pivotal relation at 18 to have the handle parts 19, 20 and the jaw parts 21, 22 as indicated. The sharpened opposite notches 21, 22' in the jaws, co-operate to cut into the insulation covering of an electric wire placed between them. The extent of the depth of out will depend upon the position of the round stop button 23 along the track slot 24 in handle 20. Said button which is on the same face of the arm 17 as is the arm 16, will intercept the arm 16, upon the occurrence of which, the longitudinal straight edge A of said arm 16 will contact and of course be tangent to the circular periphery of said button 23.

This button-has a coaxial shank'25 which is contact with the edges of the slot 24, and extends through I said slot. It carries a slightly stressed spring washer or a mere friction washer 26 and is fashioned to maintain the assembly of the unitary structure designated by the numeral 27. The axes of said shank and of the pivot 18, are parallel. The track 24 must be of special construction for the practice-of this invention, because when the track is of no particular design, some means must be provided to hold the item 27 securely at any desired position along the track since said item 27 would usually be moved byia component of the force applied to the plierhandles when edge A is tangent to the button 23.

I will now resort to Fig. 4 to show the forces acting on the button 23 when edge A is in contact therewith and the plier is in forceful grasp. Consider the shank to be round as 25', though actually it is of flattened or square cross section as shown in Fig. 1 at 25. The line B indicates the tangent line to the slot 24 and the shank 25. F indicates the force being applied to close the plier; such force being'perpendicular to line A and may be resolved into its component forces P which is perpendicular to line B and the force P" which is parallel to said line B. Force F pushes the shank against the edge of the track slot and causes no movement of the button along the slot. Force F" acts to move the item 27 along the track.

For the practice of this invention, the track 24 is so designed that the force F" is always less than is necessary to shift the item 27 along such track and I set forth the following to explain the construction of such track.

The coefiicient of friction for the surface of the item 27 and that of the arm 17, is the ratio of the force P re quired to move said item along the track slot corresponding to any normal pressure P between the surfacesand that normal pressure. If the angle between such forces is designated as 5, then the coeflicient of friction equals F"/F' and hence is equal to tangent p. If the sliding member 27 is deemed on an inclined plane whose angle of repose is P, then both said angles are equal. If the materials are such that the coefficient of friction is say 0.20, this would mean that slippage would not take place if angle 5 were less than an angle Whosetangent is 0.20, meaning one less than 11 degrees 20 minutes. Note that the angle between the lines A and B is In Fig. 5 we show one way of laying out the track slot 24, which will now be set forth. Starting with an angle P representing the edge A at the maximum stopping angle required by the plier in question, we draw a circle C representing the button 23 tangent-to line A and from its center 0 we draw a short line L making an angle of say ten degrees with A along which a suitable short length is measured from O. For convenience, we have used the radius of the circle C determining a new center 0 from which a new button C is drawn which in turn determines a new position A of the edge A. From 0 we draw a new line L making again a ten degree angle with A and by continuing this procedure a sulficient number of times, we develop the curve of the center line 24 of the slot 24 such that regardless of the position at which button 23 is placed when handle 19 is engaged with the button 23, it will make a constant angle less than with the center line of the slot 24 at that point. Hence regardless of the pressure P exerted on in sliding n st d n; piyov r 3 the handles or the position of the button 23, no slippage 9???? b an at t a tqaaa Having the center line of the slot' 24, the V of such slot is known practice and needs no further explanati n. As a u esti n, t p a i q d aw; the a aa t0, an en ar ed scale nd. than transi the slo on completion to the axis of said pivotal connection; said shank being nq it aasd n aid t ack and en a ed herewi h ion s iding movement therealong;. said member being infrictional contact With the arm having the track and manuali a by'mqaas Q 'a pa phon o e block of steel ab us d tqma e hs Punchin di o such s otis T is nv nt qn s capa le qt a iou qm s'and mi-H V ar i s apnl s q i wit qu 'd par i fr th essen ials afltllr s h t in di lQs It i er fo cndedand desired that the embodiment herein shall be deemed,"

l st a ve and. n t tzict ye an that qpatem, s all fiv al pa e tahla i e ty he ein' se orth; I erence be ha to the ollowi c aims rather than o. the sgific d s p iqn herei to nd te ope'of this 4 .0 98 6 9 id q aid PiYQ a o i n; the curve Qt Sa t a b ing a Pl ne s stan l y Perpendicular 1y slidable along such arm at all times; the other of said arms presenting a longitudinal straight edge positioned thereon whereby on movement of said arms towards each other, said straight edge will come into contact with the j round periphery 'o f said button; the characterofthe curve of the track is such vthat at any position of the shank along the track, the angle between the said, straight edge. when inv contactTwitHthe button, and the tangent to said curve whicheis also tangent to a circle deemed to be in place of the'shank, is less than the angle whose tangent V is the coefiicient of'frictio n of the arni'hauihg the track with said memberf 7 a 2. The tool as defined in claim 1, wherein the track is a slot; the shank being positioned through such slot.

References Cited in the file of this patent U IIB SIAT A ENT 1,578,438 Hintz Mar. 30, 1926 

